5b 6

var
  s: string;
  i: integer;

begin
  writeln('Введите текст: ');
  readln(s);
  s := ' ' + s;
  s := s + ' ';
  for i := 1 to length(s) do
  begin
    if s[i] = 'а' then
    begin
      delete(s, i, 1);
      insert('ку', s, i);
    end;
  end;
  writeln(s);
end.